function y=Griewank7(xx)
%Griewank

[row,col]=size(xx);
if row>1
    error('error');
end
y1=1/4000*sum(xx.^2);
y2=1;
for i=1:col
    y2=y2*cos(xx(i)/sqrt(i));
end
y=y1-y2+1;
%y=sum(xx.^2);

